There is a lack of technical solution to efficiently reduce the effect of the content of the harmonic components in the motor induced voltage and reduction of the torque oscillation of the motor with inside-placed permanent magnets in the rotor.
In US 2012/0293033 A1 the key deficiency of the exposed solution is shown in the local weakening of the rotor stack laminations, which is caused by the increased volume of the air barrier.
A rotor of the aforementioned kind is known from US 2013/0270958 A1, wherein individual gaps are provided for insertion of a single permanent magnet, wherein the central connecting element creates opposing air barriers with a rounded shape.